Partial hydrogenation of unsaturated glyceride oils



2 Sheets-Sheet 1 PARTIAL HYDROGENATION 0F UNSATURATED GLYCERIDE OILSAug. 29, 1950 Filed May 2, 1947 llama/MM5 wifi-rvu Snow,

kga. 63 Vada/'Milla Juds'anMm/ Hara@ l en/ley Aus 29, 195o v. MILLS TAL2,520,423

PARTIAL HYDROGENATION OF UNSATURATED GLYCERIDE OILS Filed Ilay 2, 1947 2Sheets-Sheet 2 Patented Aug. 29, 1950 PARTIAL HYDROGENATION F UNSATU-RATED GLYCERIDE OILS Victor Mills, Judson H. Sanders,

Hawley, Cincinnati, Ohio, Procter and Gamble Compan a corporation ofOhio and Harold K. assignors to The Ivorydale, Ohio,

Application May 2, 1947, Serial No. 745,661

Claims.

This invention relates to the partial hydrogenation of unsaturatedglyceride oils containing polyethylenic double bonds, for -use in themanufacture of plastic shortening.

The vegetable oils of primary commercial interest in this connection inthe United States are cottonseed oil and soybean oil, both of which areused in enormous quantities for the purpose. After being partiallyhydrogenated, and then deodorized, the fatty material is plasticized" bychilling it rapidly to about 50 to 65 F. and whipping it until thesuper-cooled material has largely given up its heat of crystallizationand has acquired a creamy texture. Upon standing for a short time atroom temperature to complete its setting up," the shortening acquires asoft plastic consistency which makes it suitable for working into doughsand batters for the making of various baked goods.

A shortening made in this Way, entirely from partially hydrogenated oil,tends to become inconveniently soft when its temperature is warmed a fewdegrees, and tends to become inconveniently firm when its temperature islowered a few degrees. It is thus said to have a narrow plastic range. Ashortening having a broader plastic range. i. e. a wider range oftemperatures within which it has a desirable plasticity, is produced byhydrogenating the oil slightly less and blendlng with this partiallyhydrogenated base stock, before plasticizing. a minor proportion oftrisaturated glyceride, known as hard stock. Best results. from thestandpoint of plasticity of such blended shortening, are achieved whennormal oleic acid radicals predominate in the partially hydrogenatedbase stock of the shortening; saturated acid radicals are unnecessary inthe base stock, requisite stiffness of the finished shortenlng beinginsured by the addition of suiicient hard stock. Again, thepolyethylenic fatty acid radicals (principally the di-ethylenic radical,linoleic) are susceptible to oxidative rancidity. and the stability ofthe shortening is greatly enhanced by hydrogenation of such radicals.

Thus the ideal process of partially hydrogenating oils such ascottonseed or soybean would convert all of their polyethylenic fattyacid radicals to normal oleic acid radicals, with the conversion of fewif any unsaturated acid radicals to saturated acid radicals.

In practice this ideal is never reached, partly because some of theunsaturated acid radicals are unavoidably saturated during thehydrogenation, but principally because of the inadvertent creation ofglycerldes containing isooleic acid radicals. Many of these isoolelcglycerides are (1) solid at normal room temperature, and (2) melt atslightly above this temperature. Because of the ilrst of theseproperties they add to the firming effect of the saturated radicals.frequently to such an extent that the desired plasticity is reachedbefore the conversion of all of the polyethylenic radicals is complete,with the result that the finished shortening is insuilciently resistantto rancidity. Because of the second of the properties possessed byisooleic glycerides the finished shortening softens unduly when it isheld at temperatures in the neighborhood of to 100 F., and then whenagain brought to normal room temperature it becomes undesirably rm andribby (uneven in consistency) because of the knitting or interlacing ofthe reformed crystals of isooleic esters, such shortening thus havingwhat is known as an unstable plasticity.

To state the situation differently, besides the principal desiredreaction:

(l) Polyethylenic acid radicals-normal oleic acid radicals, severalundesired side reactions simultaneously occur, including:

(2) Polyethylenic acid radicalsisomeric oleic acid radicals (3) Normaloleic acid radicals-isomeric oleic acid radicals (4) Monoethylenic acidradicalsesaturated acid radicals Reactions (2), (3) and (4) all result(sometimes to an undesirable extent) in a rming of the final shorteningwhich is produced from the hydrogenated oil. Reactions (2) and (3) tendto impart unstable plasticity to the product. Reactions (1) and (2)increase the product's resistance to rancidity. i. e. improve itskeeping qualities.

No means has as yet been discovered for totally suppressing reactions(2), (3) and/or (4) while causing reaction (l) to proceed. Some controlcan be exercised, however, over the rela.- tive rates of these severalreactions, the normal desire being to promote reaction (1) whileimpeding (or promoting to a lesser extent) reactions (2), (3) and (4).The principal difliculty standing in the way of accomplishing thisdesire is that reaction conditions which tend to suppress reactions (2)and (3) normally tend to stimulate reaction (4), and vice versa.

The general practice in partially hydrogenating an oil such ascottonseed oil or soybean oil. for use as a base stock in plasticshortening, is to choose reaction conditions best calculated to favorreaction (1) more than reactions (2). (3)

and/or (4) and to choose an endpoint which corresponds as nearly aspossible to the complete elimination of polyethylenic radicals while notentailing the production of any more of the products of reactions (2),(3) and (4) than can be helped. A compromise between these desirable andundesirable results is thus necessary in order to produce a shorteninghaving at least reasonably good keeping qualities together with at leastreasonably good plastic properties.

During the years since the advent of hydrogenated vegetable shortening,a numebr of suggestions have been made, chiefly in the realm of improvedcatalysts and in the choice of favorable temperature and pressure rangefor the hydrogenation, with the object of obtaining either improvedselection (i. e. the tendency to favor the hydrogenation of the moreunsaturated acid radicals before the hydrogenation of the lessunsaturated radicals), or a repression of isooleic formation. Thepresent invention marks a definite advance in both of these directions,and thus permits one to produce a shortening having better keepingqualities for a given consistency, or a more desirable consistency for agiven keeping quality, or some combination of these two advantages.

Prior investigators have found that "selectivity is favored by hightemperatures, hydrogenation in the neighborhood of 165 C., for example,being much more favorable to the preferential hydrogenation of linoleicto oleic than hydrogenation at 125 C. and below. The higher temperatureswhich favor selectivity" are, howevr, objectionable in that they areknown to favor the formation of isooleic glycerides. 1ncreasing hydrogenpressure and increased agitation have in the past been found to bedetrimental to "selectivity,"

In the past, the time required to hydrogenate cottonseed oil and/ orsoybean oil to a consistency suitable for use as a base stock in plasticshortening has normally ranged from about an hour to two hours, at besthalf an hour or thereabouts when the hydrogenation temperature has beensufficiently high and the catalyst sufllciently active.

We have found that when the hydrogenation reaction is greatly speededup, so that the desired endpoint is reached in a matter of a very fewminutes, by the employment of adequate amounts of highly activenickel-containing catalysts, violent agitation, and superatmospherichydrogen pressure, an unexpected degree of repression of the formationof isooleic acid radicals (reaction 2 and possibly 3) occurs, the extentof this being so beneficial as to more than offset those aspects of theprocess which are unfavorable from the point of view of obtainingselectivity This unprecedented speeding up of the reaction wasimpractical in batch type hydrogenation apparatus heretofore used,because accurate end point control is not feasible in such apparatuswhen the reaction must be terminated within a few minutes of its start,and also because of serious inadequacies of agitation and of heatremoval. We therefore have developed a novel form of continuous process,and in this process we employ a special expedient which makes itpossible to maintain a constant reaction rate and therefore to attainaccurate end point control, this expedient being the continuous removalof the heat of reaction as it is liberated thus keeping the temperatureof the oil practically constant during its hydrogenation.

The process herein described and claimed is generally applicable to thetreatment of those vegetable oils which have iodine values between aboutand 140. such as cottonseed oil. peanut oil, sesame oil, and soybeanoil. to produce partially hydrogenated fats having iodine values betweenabout 60 and about 90, for use either alone or blended with hard stock"and/or with unhydrogenated oil in the manufacture of plasticshortenings. It will also find application in the partial hydrogenationof lard, particularly to improve its keeping qualities, and in thepartial hydrogenation of marine oils. Mixtures of any of these oils withone another or with other glyceride oils such as palm oil are alsosuitable for treatment by our process.

More specifically, our process comprises conducting the catalyticpartial hydrogenation oi natural glyceride oils containing polyethylenicfatty acid radicals in a continuous manner and within certaintemperature and pressure ranges in the presence of an adequate amount ofhighly active catalyst, and under sumciently violent mechanicallyinduced agitation to cause the chemical addition of hydrogen to theethylenic carbon atoms to proceed at exceptionally rapid rates, animportant feature of the process being the continuous removal ofreaction heat, whereby superior product characteristics and uniformityof product quality are obtained.

Objects of the invention include the aforementioned principal objectlvesof obtaining improved keeping quality for a given plasticity, andimproved plasticity characteristics for a given keeping quality, andalso the following:

To provide a method of producing hydrogenated oil of improved quality asa result of its very short exposure to high temperature.

To produce partially hydrogenated vegetable oil containing fewerisooleic acid esters than in comparable products made by commonly usedprocesses heretofore available.

To produce partially hydrogenated vegetable oils having lower iodinevalues for a given degree of plasticity as compared with similar oilsproduced by prior hydrogenation practices.

To produce base stock for hydrogenated plastic shortenings having awider temperature range of desirable plasticitles than the rangeobtainable in similar shortenings made from the same oil by priorhydrogenation practices.

To produce base stocks for hydrogenated plastic shortenings havingexcellent stability of plastic properties when subjected to storagetemper- .tures in the neighborhood of 90 F. and when subsequently usedat normal room temperatures.

To provide a process for the partial hydrogenation of vegetable oils foruse in plastic shortenings which permits obtaining superior uniformityof product composition, as a result of precise temperature and pressurecontrol and endpoint control.

To provide a process having economies in operation resulting from therapidity and uniformity of the reaction rate, including greater re-usevalue of catalyst. decreased cost of maintaining re-use hydrogen freefrom catalyst poisons, and improved operating eiiiciency of hydrogengenerating plant and hydrogenating plant due to uniform productionscheduling.

A suitable form of apparatus for carrying out our process is illustratedin the accompanying drawing. in which:

Figure l is a schematic flow chart showing the principal elements of atypical continuous hydrogenation system: A

Figure 2 is a side elevation of mechanically agitated continuoushydrogenator vessel;

Figure 3 is a vertical section of the vessel shown in Figure 2;

Figure 4 is a horizontal section of the vessel, taken on the line 4-4 ofFigure 3;

Figure 5 is a fragmentary vertical section of the inner chamber of thissame vessel, showing in perspective some of the hold-back baffles, orstators, and one of the horizontal bames;

Figure 6 is a fragmentary sectional view taken on the line I-B of Figure2; and

Figure 7 is a graph indicating reaction rates versus temperatures.

The detailed structure of the apparatus illustrated in these drawingsforms no part of the present invention, and very favorable results havebeen obtained with apparatus of quite diderent design.

Referring to Figure l, the unsaturated liquid material to behydrogenated is delivered from supply tank I0 by means of pump i2through a tubular preheater I3 to and through the hydrogenator I4. Asuitable hydrogenation catalyst suspended in a small quantity of asuitable liquid (which may often be a portion of the material to behydrogenated) is delivered from catalyst supply tank IB by means of pumpIB either directly into the hydrogenator, or (as shown) into thepipeline which is delivering the main supply of material to behydrogenated from the preheater to the hydrogenator, for example, atpoint i1. A continuous supply of hydrogen, or a suitablehydrogen-containing gas, is introduced into the same pipeline at anotherpoint ahead of the hydrogenator, for example at point I3, the hydrogensupply being drawn from a suitable reservoir or supply, as illustratedat I3, by means of compressor through a pressure regulating valve 2i.While flowing through the hydro genator i4, the mixture of the liquidmaterial to be hydrogenated, the catalyst, and the hydrogen is subjectedto violent agitation to bring these three materials into intimatecontact with one another and to bring about a rapid movement of theindividual particles of each of the non-liquid phases in contact withthe particles of the liquid phase, thus promoting a high velocity of thehydrogenation reactions which occur in this vessel. The heat of reactionwhich is liberated is preferably (especially when only partiallyhydrogenating an unsaturated material) completely, or at least for themost part, removed continuously by circulating a cooling medium througha jacket surrounding the reaction space in the hydrogenator, the coolingmedium being circulated by means of pump 22, and the heat being removedfrom the cooling medium in heat exchanger 23. The reaction mixturepassing through hydrogenator I 4 is maintained at super atmosphericpressure, and this pressure may conveniently be regulated `by means ofthe ad justabie relief valve 24 in the outlet line leading from thehydrogenator. If a surplus of hydrogen is used, over that which reactswith the oil and that which remains dissolved in the liquid leaving thehydrogenator, this surplus may be separated and bled oil through the topof small tank 25. The hydrogenated material leaving the hydrogenator iscooled by means of heat exchanger 28, and any remaining gas which hascome out of solution subsequent to the drop in pressure at valve 24 isthen separated from the hydrogenated material, and the catalyst isremoved by i'lltratlon or by any other convenient method in apparatusnot illustrated in the drawing.

The hydrogenator i4 of the system just described may be constructed asshown more particularly in Figures 2 to 6, inclusive, in which isillustrated a preferred type of hydrogenating apparatus. Thus thehydrogenator may comprise an outer jacket 30, provided with an expansioncoupling 3l to relieve strains caused by temperature changes, and aninner cylinder 32, the jacket and cylinder defining an annular space 33within which is circulated a. fluid coolant, the inlet and outletconduits for the coolant being shown in Figure 2 at 34 and 35respectively. A hollow shaft 33, of substantially less diameter thancylinder 32, is disposed coaxially within the cylinder and supported forrotation about its vertical axis, shaft 38 and cylinder 32 defining anannular reaction passage in which the mixture of the liquid fattymaterial, the hydrogen, and the catalytic agent, is intensely agitatedwhile flowing in an upward direction, being introduced through an inletpassage 39 formed in an annular plate 40 at the lower end of cylinder32, and discharging through an outlet passage 42 in an annular plate 43at the upper end of cylinder 32.

The hydrogenator is closed at its upper end by a cap structurecomprising plate 43 and closure members 46 and 46. the several partsbeing bolted together as shown more particularly in Figure 3. A radialthrust bearing 43, seated in member 45 and retained in position bymember 4B engages and supports a shaft 49 which extends within and issecured to the hollow shaft 33. whereby the latter is journaled forrotation. Received within and secured to shaft 33 at its lower end is acoupling element 5|; a drive shaft 52, disposed coaxially of shaft 38,extends within and is secured for rotation with coupling element 5I.Drive shaft 52 is journaled for rotation in the supporting basestructure indicated generally at 53, the hydrogenator being suitablymounted on this base structure. A motor having a shaft 56 drives shaft52 through bevel gearing 51, whereby the hollow shaft 33 is rotatedrapidly. It will be appreciated that the details of this constructionform no part of the instant invention and may be varied widely.

The annular reaction passage between shaft 33 and cylinder 32 is dividedinto a series of compartments or reaction zones by means of a pluralltyof horizontally disposed annular disks or baffles 80, the baiiles beingspaced longitudinally of the hydrogenator. The outer diameter of eachbaille Bil is such that the baiiies t snugly within cylinder 32, theinner diameter being slightly larger than the outer diameter of shaft38, so as to afford slight mechanical clearance therebetween. Thereacting materials owing upwardly are thus caused to flow through therestricted annular passages defined between shaft 38 and baffles 3B inmoving from each compartment or reaction zone to the next higher zone,retention of the materials in each zone for a substantial length of timebeing assured. Channeling or too rapid movement of insuillcientlyreacted materials through and out of the hydrogenator, is therebyavoided. The bailies may be retained in proper spaced relation by aseries of spacing sleeves, the several sleeves fitting snugly withincylinder 32, so that each of the baflies is clamped between an adjacentpair oi sleeves Il. Each of andere the sleeves ll may be formed withlongitudinally extending slots il, as shown more particularly in Figures3 and 5, to reduce the weight of the sleeves and to increase the heattransfer surface and the volume and capacity of the several reactingzones. An emcient hydrogenator may be provided with as many as 1lbaiiles, or even more, so as to provide 12 or more reacting zones, butthe number of zones may be varied widely.

In order to effect intense agitation of the material, each zone may beprovided with a series of agitator blades 85, and with cooperatingstator blades or stationary baffles B8 located above and below theagitator blades. The agitator blades ll are disposed radially of and arebolted securely to the hollow shaft 38 in circumferentially spacedrelation, one such series of agitator blades being shown in dotted linesin Figure 5. In order to prevent leakage of the reacting materials pastthe securing bolts to the interior of the shaft a sleeve 68 extendingwithin and over the major portion of the length of shaft 3l, is weldedto the latter at each end. The circumferentially spaced stator blades I8are likewise disposed radially of the axis of shaft 38, and are boltedor are otherwise secured to the sleeves Iii adjacent to each of theannular disks 50. preferably intermediate the slots 82 formed in sleeve5i, as shown in Figure 5. It will be observed that each reaction zone isprovided with one series of agitator blades 85 and two series ofcooperating stator blades 68, the latter acting to resist continuousswirling movement of the reacting materials about shaft lil andotherwise serving to increase the degree of agitation imparted to thematerials. Preferably, blades 66 and 66 in adjacent series are sodimensioned as to afford only the necessary mechanical clearance betweeneach other; similarly, only mechanical clearance is afforded between thestator blades 86 and the shaft 38 and between the agitator blades 55 andthe sleeves il.

In the particular hydrogenator illustrated, we effectively avoid unduecontamination of the nnished product with raw oil or with insumcientlyhydrogenated oil by a combination of two provisions: first, therelatively long passage between the walls of cylinder 32 and the centralshaft Il through which the reaction mixture passes on its way from theentrance to the exit of the hydrogenator, the flow through this passagebeing interrupted repeatedly by a series of transverse agitatorsseparated from one another by a corresponding series of stator bladestending to break up swirling induced by the agitators; and second, thehorizontal circular bames, elements Il, which subdivide the reactionzone into a plurality of lesser zones each communicating with theadjoining one by means of a passage of greatly restrictedcross-sectional area. The importance of these factors will be pointedout later on.

When the process of the present invention is in operation under typicalconditions, with the iiow of oily liquid, suspended catalyst, andhydrogen passing at uniform rates in contact with one another throughthe reaction vessel under conditions of extreme turbulence, thetemperature of the liquid is established at a chosen value (ashereinafter discussed) by adjusting the pressure of the steam or thetemperature and rate of flow oi' other heating medium through the jacketof the oil preheater, and this temperature is maintained with but littleor no rise as the oil passes through the hydrogenator by controlling thetemperature or rate o! now of the water or other cooling medium throughthe jacket lili*- rounding the hydrogenator.

The degree of reaction, or completeness of hydrogenation (as measuredfrom time to time by determining the iodine value, or the refractiveindex, or the congeal point, or the titer, or other index, of samples ofthe hydrogenated liquid withdrawn from the system after the reaction hasceased) may conveniently be controlled by regulating the rate oi.'introduction oi' the liquid to be hydrogenated. As this liquid rate isvaried one may simultaneously and correspondingly vary the rates of feedof the catalyst slurry and the hydrogen, thus maintaining constantproportions of catalyst and hydrogen in relation to the liquid feedrate, or one may alternatively keep one or both of these secondary feedrates constant, or vary it independently of the liquid feed rate, thusgaining an independent or supplementary control over the extent oi' thehydrogenation which occurs. The amount oi hydrogen which is supplied tothe hydrogenator should of course be adequate for the degree ofhydrogenation desired, and may conveniently be somewhat in excess ofthis amount in order to insure utilizing the maximum hydrogenatingcapacity ci the hydrogenator.

An outstanding aspect oi' our invention is the discovery of surprisingimprovements in product quality which result directly or indirectly fromthe very high reaction rates which it employs, even when other operatingvariables of the procress are within undesirable ranges from thestandpoint of selection, as contrasted with the corresponding productcharacteristics produced by the slower hydrogenation rates (atcorresponding temperatures) which characterize prior practices.Advantage oi these quality improvements may be taken in severaldifferent ways, depending largely upon the correlation of the reactiontemperature and hydrogen pressure. We will discuss this subject in thenext four paragraphs in terms of cottonseed oil hydrogenated to aniodine value in the neighborhood of 70 to 78, this hydrogenated productthen being blended with 6% to 6.5% of hard stock and plasticized toproduce plastic shortening having a consistency at room temperature inthe general range of that of the commercial hydrogenated vegetable oilshortening Crisco" and/or oi' that of some of the best grades of ediblelard, This discussion (except as concerns the fourth preferred regiondescribed below) is equally applicable to the similar treatment ofsoybean oil hydrogenated to the same consistency value (corresponding toa somewhat higher iodine value than with cottonseed oil) or to blends ofcottonseed oil and soybean oil, and to other similar unsaturatedglyceride oils and fats suitable. for use in the manufacture ofshortening. It is also applicable, although with less pronounced benets,to such oils hydrogenated to end points outside of the preferred limits,l0 to 78, but usually not beyond the wider limts, 60 to 90.

Preferred region 1.-We have found that by employing moderately highreaction temperatures, from about C, to about 180 C., and by elevatingthe hydrogen pressure to within an especially advantageous range whichextends from about 20 to about 60 pounds per square inch, our processproduces shortenings having materially superior keeping qualities tothose shortenings of equal consistency value produced by slowerprocesses. Example l is typical of this use of our invention. Pressuressubstantially below 20 ascuas pounds do not produce a fast enoughreaction to gain this outstanding benet, and pressures substantiallyabove pounds tend to be too seriously detrimental to selectivity. Withinthis critical combination of temperature and pressure ranges theinjurious effect of pressure upon selectivity and the stimulating effectof the relatively high temperature upon isooleic formation are found t0be more than offset by what appears to be a suppression of the formationof isooleic acid radicals due directly or indirectly to the pressureemployed coupled with the other favorable conditions inherent in ourprocess, with the net result that the hydrogenation is carried to a.substantially lower iodine value than would be normal to at tain a givenconsistency, and a shortening having superior keeping qualities isthereby obtained. This result could not be predicted from informationhitherto available. One could, of course, stop the hydrogenation at apoint which gives a normal keeping quality, and thus obtain anabnormally soft product if this should be desired.

Preferred region 2.-Anothcr preferred Way which we have discovered oftaking advantage of the quality improvements which depend upon theextreme rapidity of our` process is in the employment of relatively lowtemperatures, from about C. to about 120 C., at correspondingly higherpressures, within a range which extends upwards from about pounds persquare inch. Within this especially advantageous combination of lowtemperature range and high pressure, the suppression of the formation ofisooleic acid radicals is so great that it offsets the injuries effectsupon selectivity of both the low temperature and the high pressure, withthe net results that when the hydrogenation is carried to a givenconsistency value, as compared with corresponding prior shortenings, aproduct having keeping qualities about equal to those of thecorresponding prior shortenings and having superior plasticcharacteristics is produced. Of the glycerides in the hydrogenated oilwhich are solid at room temperature (i. e. glyceridcs of saturated acidsand oi' isooleic acids) and which impart body and a de- V;

gree of firmness to the shortening, a greater proportion in this case-ascompared with more slowly hydrogenated oils-are saturated glycerides anda lesser proportion are isooleic glyccrides. solid types of glyceridesimparts to the shortening a wider plasticity range fi. e. a wider rangeof temperatures in which desirable plasticity values exist), a bettertexture, and an excellent stability 0f plasticity following storage atsummer temperatures in the neighborhood of 90 F. Example 2 is typical ofthis use of our invention.

Preferred req-0n 3.-A third preferred temperature-pressure region of ourprocess lies between temperatures of C. to 150 C., with hydrogenpressure increasing with temperature. In this region the preferredpressure is p. s. i. or above for 110 C. hydrogenation temperature, 160p. s. i. or above for 130 C., 300 p. S. i. or above for 150 C, Thisregion (3) is adjacent to region f2) and accomplishes similar benefitsThe increasingly had influence of increasing temperature upon isooleicformation is compensated in this region by the increasingly beneficialinfluence of short hydrogenating time, a combined result of highertemperature and higher pressure, and the bad influence of increasing`pressure on selection is compensated by the good influence upon thisfactor of increasing temperature. Within this preferred region thehydrogenatoti 'I'his shift in proportions of these two :f

conditions should be so chosen as to obtain a, rate equivalent to aniodine value drop per minute of at least 5 units at 110 C.. at least 14units at C., and at least 35 units at 150 C., with minimum rates forintermediate temperatures lying on a smooth curve connecting these threepoints. Example 10 is typical of operation within this region,

Preferred region 4.-A fourth manner of obtaining improved productcharacteristics by means of our process is in the hydrogenatlon o1'cottonseed oil (or cottonseed oil-soybean oil blends) to produce thatspecial type of plastic shortening which has exceptionally good keepingqualities even when incorporated in baked goods which undergo extremeexposure to high temperature, as in the making of crackers and biscuitswhich may then be kept for a long time before being consumed. It ispreferred to hydrogenate the oil for such a shortening untilsubstantially all linoleic glycerides have been converted to a lessunsaturated condition, which with cottonseed oil usually requires goingto an iodine value below '70. This also calls for the employment of atemperature which produces good selectionf preferably within the rangeC. to 180 C., and also for a pressure which is not detrimental to"selection, preferably a superatmospheric pressure not higher than 20pounds per square inch. Although such low pressures do not producereaction rates as fast as are otherwise obtainable, the employment ofextremely violent agitation and adequate amounts of active catalystnevertheless result in hydrogenation rates within these temperature andpressure ranges of over 5 iodine value units drop per minute, and as aconsequence the formation of isooleic glycerides is minimized. Thus Weare able to produce a product having esceptional keeping qualities and aconsistency more suitable for effective working in bakery mixingmachines than similar shortenings made by slower hydrogenationprocesses. Example 7 typifles this application of our process.

One may if he desires employ our process with temperature and/orpressure conditions intermediate between the four sets of conditionsjust discussed, for example temperatures between 120 C. and 150 C. withhydrogen pressures between 40 and 100 p. s. l., thus achieving thosegeneral benefits which accompany our process, particularly freedom fromhydrolysis and thermal decomposition, because of the very short time theoil is held at elevated temperature, and uniformity of productcomposition and characteristics, because of the close and uniformcontrol of hydrogenating conditions. Example 9 illustrates this methodof employing our invention.

To facilitate an understanding of the invention, including its severalspecial aspects, its employment in a number of typical hydrogenationswill be described.

Example 1.-Rened and bleached prime cottonseed oil containing 0.04% ofits weight of nickel, in the form of a suspension of a nely dividedpromoted nickel catalyst having an activity of 5.7 units (as hereinafterexplained), was pumped at a rate of 2.44 pounds per minute through apreheater, in which its temperature was raised to 166 C., and thenceinto and through a small sized continuous hydrogenator resembling theone shown in Figures 2 to 6 except that it had only three circularbaffles, elements 60, The internal dimensions of this hydrogenator werea diameter (element $2) oi' 4 inches, a height of 60 inches, and a i'reespace volume of 353 cubic inches (of which about 78% is occupied by oiland 22% by gas under average operating conditions); and the speed of itsagitator was 1000 R. P. M. The arrangement of the equipment was likethat shown in Fig. 1, except that the catalyst feed tank I5 wasdispensed with, the catalyst being added to the oil in supply tank lwhich was provided with a mechanical agitator. A stream of electrolytichydrogen, amounting to about 1.45 cubic feet per minute under standardconditions (all gas volumes will be expressed in terms oi' standardconditions unless otherwise stated), was introduced at a pressure of 50pounds per square inch (all pressures are superatmospheric gaugepreseures) into the oil feed line at a point near its point of entryinto the hydrogenator. A sumcient flow of cooling water was passedthrough the jacket of the hydrogenator to keep the outlet hydrogenatedoil temperature at l68i1 C. A bleed of 0.25 cubic foot per minute ofsurplus hydrogen was Withdrawn from the oil just beyond its outlet fromthe hydrogenator, the oil was then reduced in pressure to a few poundsabove atmospheric, was then passed through a tubular cooler in which itstemperature was reduced to about 60 C., was then passed through anothervented tank from the top of which a small amount of unconsumed gas waswithdrawn, and the substantially gas-free oil was then passed through afilter press for the removal of catalyst.

By this process the cottonseed oil was reduced in iodine value fromabout 110 to 75.7 in 3.4 minutes, the average hardening rate being 10.2iodine value units drop per minute. A one gram sample of thishydrogenated oil when subjected to a standard oxygen absorption testabsorbed 3 c. c. of oxygen in 24 hours. The consistency of the productof this example, when made into plastic shortening, was determined byblending 6 parts of substantially fully hydrogenated cottonseed oil,called "hard stock," with 94 parts of the 75.7 I. V. product,plasticizing this blend by chilling and agitating in a known mannerunder standardized conditions and measuring the consistency of theresulting plastic shortening by means of a standardized penetrationtest.

For purposes of comparison another portion of the same cottonseed oiland catalyst slurry was hydrogenated by the conventional batch method at165 C., atmospheric pressure, with moderate mechanical agitation, to thesame degree of consistency, similarly determined. The time required inthe batch method to reach this common consistency value. which occurredwhen the iodine value reached 81.0 (over I. V. higher than in the caseof the continuous process), was 35 minutes. When subjected to the sameoxygen absorption test a one gram sample of the batch-hydrogenated oilabsorbed the 3 c. c. of oxygen in 18 hours.

Thus the fat processed by our rapid continuous process had an indicatedkeeping quality about 33 per cent better than that of the i'at ofcomparable consistency made from the same oil by a conventional batchmethod, this being due to a lower linoleic content in the former. It waspossible to reach this lower linoleic content in our process byminimizing isooleic formation, with its attendant firming eilect.

Another conventional (though abnormally rapid) comparative batch run wasmade 0n an.-

other portion of the same oil, the temperature again being 165 C. butthe pressure being 50 lbs. (the same as in the continuous run). To reachthe same consistency value (adjusting all actual results to thiscomparable basis by applying well established correction factors) thetime required was 9 minutes, the iodine value of the hydrogenated oilwas 80.0 and its 3 cc. oxygen absorption time was 19 hours. This productthus was also inferior to the one made by our process.

Example 2.--With the same apparatus as in Example 1, except that theagitator speed was 580 R. P. M., another lot of refined and bleachedcottonseed oil was hydrogenated to an iodine value of 74.5, under thefollowing conditions:

Oil and catalyst supply rate pounds per minute-- 1.76 Amount of Ni inthe oil.. percent by weight-- 0.1 Activity of catalyst units-- 5.4Hydrogen inlet rate C. F. M.-- 1.2 Surplus hydrogen outlet rate- -C. F.M.-- 0.3 Hydrogen pressure -p. s. i.-- 150 Oil inlet temperature C.--110 Oil outlet temperature il C.-- 112 Av. time of oil inhydrogenatorminutes 4.8 Total I. V. drop 35.5 I. V. drop per minute.average 7.4

When blended with 6.25% of its weight of substantially fullyhydrogenated cottonseed oil (iodine value about 8) and plasticized asexplained in the fourth from last paragraph of Example l, the productthus produced had a penetration value of 232 units at 70 F. and thisvalue increased (i. e. the product softened) 78 units when warmed to F.

For comparison another portion of the same oil and catalyst wassubjected to rapid batch hydrogenation at a temperature of to 113 C., ata pressure of p. s. i., employing mechanical agitation, to substantiallythe same iodine value as in the continuous process (specincally, to 74.1iodine value), the time required being 19 minutes, and was blended withenough hard stock (7 6,11. to produce a plasticized shortening havingthe same 70 F'. penetration value (232 units) as that produced from thecontinuously hydrogenated material. The penetration value of this secondlot of batch-hardened shortening increased 97 units upon warming from 70F. to 90 F. and it was undesirably ribby" or uneven in consistency duemainly to a higher content of isooleic acid esters (5.7% isooleic incombined fatty acids in continuous product as compared with 8.6% in thebatch product).

The oxygen absorption time of the continuously hardened oil was 14hours, and that of the batchhardened oil was also 14 hours.

Thus the shortening produced from continuously hydrogenated oil had asmoother consistency than that made by the batch process, and auniformity of consistency over a range of temperatures commonlyencountered in kitchen and bakery practice such that it varied only 80per cent as much as the batch-hardened lot.

Example 3.-With the same apparatus as in Example 2, a lot of refined andbleached soybean oil was hydrogenated to an iodine value of 82.8, underthe following conditions:

Oil and catalyst supply rate pounds per minute-.. 2.14

13 Hydrogen pressure p. s. i.-- 25 Oil inlet temperature C. 165 OiloutletI temperature C. 168 Av. time of oil in hydrogenatorminutes 4Total I. V. drop 52.2 I. V. drop per minute, average 13 For comparisonanother lot of the same oil was hydrogenated with the same catalyst (butwith the amount reduced to 0.04% Ni) under typical factory conditionsfor batch operation. The temperature was 165 C., the hydrogen pressurejust above atmospheric, the agitation was that provided by vigorous gasow, the time of hydrogenation was 48 minutes, and the nal iodine valuewas 81.9.

The blended, plasticized shortening of the continuous process had apenetration value of 235 units at 70 F., whereas the comparable batchproduct was ilrmer by 40 penetration units. (If the iodine values of thetwo had been the same, the batch product would still have been firmer byabout 34 units.)

Example 4.-In a large hydrogenator similar to that illustrated in Figs.2 to 6, having an internal diameter of 8 inches, an internal height of97 inches, a free space of 2164 cubic inchesl, and an agitator speed of200 R. P. M. operated in the general manner of Example l except that thecatalyst (slurried in oil) was fed separately into the hydrogenator andthat puriiled hydrogen made by the steam iron process was used, a lot ofrefined and bleached cottonseed oil was hydrogenated under the followingconditions:

Oil supply rate pounds per hour 350 Catalyst slurry rate do- 7.56Percent Ni in catalyst slurry 5.0 Amount of Ni addition percent of wt.of oi1 0.11

Activity of catalyst units 5.4 Hydrogen inlet rate cubic ft./hr. 204Surplus hydrogen outlet rate cubic ft./hr. 30 Hydrogen pressure p. s.i.-- 150 Oil inlet temperature C.-- 89 Oil outlet temperature C. 92 Av.time of oil in hydrogenator minutes 8.6 Initial I. V 112 Final I. V 77I. V. drop per minute, average 4.1

Example 5,-In the same hydrogenator as in Example 4, operated in thesame general manner, a lot of refined and bleached cottonseed oil washydrogenated under the following conditions:

Oil supply rate pounds per hour-- 1000 Catalyst slurry rate do 17.6Percent Ni in catalyst slurry 2.5 Amount of nickel addition percent ofwt. of oil-- .044 Activity of catalyst units 5.0 Hydrogen inlet rate C.F. H. 634 Surplus hydrogen outlet rate -C. F. H. 30 Hydrogen pressure p.s. i.-- 50 Oil inlet temperature C. 160 Oil outlet temperature C. 167Av. time of oil in hydrogenator minutes 3 Initial I. V 112.0 Final I. V69.5 I. V. drop per minute, average 14.2

Example 6.-In the same hydrogenator as in About 78% o! which is occupiedby oil under average operating conditions.

14 Example 4, operated in the same general manner except that there wasno bleed of surplus hydrogen, a lot of refined and bleached cottonseedoil was hydrogenated under the following conditions:

Oil supply rate pounds per hour-- 505 Catalyst slurry rate do 8.8Percent Ni in catalyst slurry 5.0 Amount of nickel addition percent ofwt. of oil-- .087 Activity of catalyst 4.7 Hydrogen inlet rate C. F. H.297 Hydrogen pressure -p. s. i.-- 100 Oil inlet temperature C. 106 Oiloutlet temperature C. 103 Av. time of oil in hydrogenator minutes \5.94Initial I. V 112.0 Final I. V 70.6 I. V. drop per minute. average 7.0

The hydrogenated products of Examples 4, 5 and 6, when mixed with minorproportions of hard stock," deodorized, and plasticized, producedshortenings having excellent plastic properties and good keepingqualities. Whereas conventional batch hydrogenation causes a partialhydrolysis amounting to an increase of about .03% to 0.10% in the freefatty acid content ol refined cottonseed oil hydrogenated to about 75 I.V., our continuous process causes scarcely any hydrolysis, raising thefree fatty acid content only about 0.01%.

In place of the cottonseed oil employed in Examples 4, 5, and 6, one mayemploy any other refined and bleached oil or fat containingpolyethylenic double bonds which is suitable for making base stock forhydrogenated shortening, the only substantial difference being that theinitial and final iodine values will vary depending upon the individualcharacteristics of each oil.

Example 7.-In the same hydrogenator as 1n Example 4, operated in thesame general manner, two equal portions, A and B, of a mixture of equalparts of refined and bleached cottonseed and soybean oils werehydrogenated under the following conditions:

Oil supply rate. 39o im Catalyst slurry ratc. 7. 64 7 M Ni in catalystslur .89 F mi Amount o! Ni adrllilon prrcciit of wt. of oiLY ll5 .liuActivity of catalyst 4. i 4 6 Hydrogen inlet rute ru. ft/mimlte 5. 9 5`Fi Surplus hydrogen outlet mtr cu. lt.rxninute 0. 6 '0 r' Hydrogenprcssurc lhs../sq. inA 19 li Oilinlot tempcrature f" 166 IM Oil outlettemperatura C 168 mi AV. time of oil in hydrml um minutes 7. 7 T iInitial I V 124. 2 124 2 Final l. V 67.6 TI 8 I. V. drop per minute.average. 7. 5 7

For comparison a third portion, C, of this mixture of oils washydrogenated by a typical factory batch procedure, at 162-l68 C., underabout l0 pounds pressure, in 65 minutes to an iodine value of 71.3.

Each of the three hydrogenated products was blended with 2% of hardstock, deodorized, and plasticized under comparable conditions. The timerequired for a one gram sample of each to absorb 3 c. c. of oxygen underthe same standardized test conditions as those employed in testing theproducts of Examples l and 2, and the penetration values of each at 70I". were as follows:

A Il C Oxygen absorption time, hours 151i i12 136 Penetration value 153217 lill By interpolation between A and B. one would expect that aproduct having an oxygen absorption time of 136 hours would have apenetration value of 182. The batch hardened product having this oxygenabsorption time was actually, and undesirably. much firmer, having apenetration value of 161.

Example 8.In the same hydrogenator as in Example 4, operated in the samegeneral manner, a mixture of equal parts of refined and bleachedcottonseed and soybean oils was hydrogenated under the followingconditions:

We have found that when cottonseed oil and at least an equal amount ofsoybean oil are hydrogenated in our process as mixtures, a producthaving a better keeping quality is obtained for a given penetrationvalue than would be the case if the same oils were hydrogenatedseparately and then blended in the same proportions. The following tableillustrates this:

Oxygen absorption time for' shortening having 70 F. penetration valueOil Proportions Cottonseed Soybean Actual Expected Exceptionally goodshortenings may be made by employing in their composition at least twothirds of such a continuously hydrogenated mixture of 50 to 90% soybeanoil and 50 to 10% cottonseed oil.

Example 9,-In the same hydrogenator as in Example 2, operated in thesame general manner, a lot of refined and bleached soybean oil washydrogenated to an iodine value of 81.3 under the following conditions:

Oil and catalyst supply rate lbs./min 1.65

Amount of Ni in the oil per cent-- .06 Activity of catalyst 5.0 Hydrogeninlet rate C. F. M 1.56 Surplus hydrogen outlet ratecu. ft./min 0.3Hydrogen pressure Iba/sq. in-- 50 Oil inlet temperature C.. 140 Oiloutlet temperature C 141 Av. time of oil in hydrogenator minutes 5.1

16 Total I. V. drop 53.7 I. V. drop per min., average 10.5

Example 10,-In the same hydrogenator as in Example 1, but equipped with11 circular bailles, element 6B, and with the catalyst added as aseparate slurry. a mixture of equal parts of cottonseed oil and soybeanoil was hydrogenated as follows:

Oil supply rate lbs/hr-- 203 Catalyst slurry rate lbs./hr 4.99 Per centNi in catalyst slurry 3.0 Amount oi Ni addition per cent of wt. of

oil 0.074 Activity of catalyst l 6.9 Hydrogen inlet rate C. F. M-- 2.78Surplus hydrogen outlet rate C. F. M- 0.50 Hydrogen pressure .f P. S. I200 Oil inlet temperature C- 124 Oil outlet temperature C 127 Avg. timeof oil in hydrogenator rninutes 2.5 Initial I. V 125.0 Final I. V 77.7I. V. `drop per minute. avg 18.8

The resulting product had excellent keeping qualities combined with goodconsistency, and was substantially equivalent in these respects to theproduct oi' Example 8.

It is understood that the material to be hydrogenated and the hydrogensupply will normally be as free as is practicable from such impuritiesas would hinder the reaction. Freedom from compounds of sulfur isespecially important, within limits readily attainable in currentcommercial practice.

Broadly speaking, the temperature to be employed in hydrogenating oilsfor use in plastic shortening by our process may be selected within therange from about 60 C. to about 180 C. Below 60 the rate is undesirablyslow, and above 180 C. the product quality tends to suffer due tothermal breakdown. The choice of a particular range between these broadextremes is of importance depending upon the particular productcharacteristics desired, as previously indicated. Higher temperatures,within the broad range of our process, very definitely speed up thereaction when other controls are held constant. This effect isillustrated in a typical case by curve C of Fig. 7, as later explained.

The pressure of the gas phase in the present process when substantiallypure hydrogen is employed, or the partial pressure oi the hydrogen inthe gas phase when a hydrogen-containing gas is used, will preferably bea superatmospheric pressure not exceeding about 500 pounds per squareinch, measured at the gas inlet to the hydrogenation zone. We havealready indicated the manner in which different pressures within theseextremes influence the resulting product characteristics. At ahydrogenaton temperature of 165 C. for example, the rate ofhydrogenation in our process may be increased at least threefold byincreasing the hydrogen pressure from atmospheric to 30 pounds persquare inch above atmospheric, and the rate at a pressure of poundsshould be two to three times the rate at 30 pounds, all other controlsbeing constant.

One oi' the factors which we have found to be essential for ourabnormally rapid reaction rate is a catalyst of high activity. We prefera catalyst having an activity of at least four units on the scale ofvalues which is explained in the next paragraph, and we have normallyemployed a catalyst having an activity of about five units. Catalystscomposed principally of nickel, promoted if desired by metals (or theiroxides) such as copper, chromium, cobalt, zirconium, thorium, or otherknown catalyst promoters, are preferred. High activity catalysts madefrom noble metals, such as platinum and palladium, may be employedalthough their high cost makes them commercially unattractive. Metalsulfide catalysts have been found unsatisfactory for use in our process.

To determine the activity of nickel-containing hydrogenation catalystsin comparable numerical terms, a representative sample of the catalystis employed to hydrogenate cottonseed oil under carefully standardizedconditions and the resulting drop in the butyro-refractive index of theoil is reported as the activity value of the catalyst. For this test along-neck fiat-bottom glass flask of 260 milliliter body capacity may beemployed as the hydrogenation vessel, this flask being fitted with acork through which pass the stem of a thermometer whose bulb is immersedin the oil in the flask, a close fitting bearing for* an agitator shaft,a metallic tube for the introduction of hydrogen leading down and aroundthe agitator and terminating directly under and pointing upward towardsthe center of the agltator. and a metallic tube to serve as an outletfor excess hydrogen. The agitator consists of a horizontal one-inchlength of steel tubing having a one-eighth inch bore, welded at its midpoint to the lower extremity of a vertical steel agitator shaft andhaving a one-eighth inch hole drilled through its wall at a pointdiametrically opposite and below its point of attachment to this shaft.The agitator clears the bottom of the flask by about one and one-fourthinches, and its shaft is directly connected to a motor which operates at3500+200 R. P. M. A vertical baffle may be employed if needed to preventa vortex effect such as might reduce the effectiveness of the agitation.The hydrogen outlet tube leads to the lower portion of a small bottlewhich is about three-fourths filled with cottonseed oil, For thepurposes of this test one needs a cylinder of compressed electrolytichydrogen, a supply of kieselguhr equivalent in quality toJohns-Manvilles Celite guhr, grade FC (or other good grade guhr known tobe acceptable in glyceride oil hydrogenation) and a supply of good graderecently refined and bleached cottonseed oil. This oil should be fullyrefined with caustic, and preferably rebleached in the laboratory forminutes with 6% of a good grade of fuller's earth (such as GeneralReduction Companys Carlton or Pikes Peak earth) at 105 C., followed byfiltration. The flask is charged with 200 grams of this oil, and to thisare added an amount of the catalyst which contains just 0.20 gram ofnickel, and 0.80 gram of the guhr. The contents of the flask are mixedand a few grams are filtered and the refractive index of the filtrate ismeasured. The flask is then placed in an oil bath which entirelysurrounds its body and extends at least an inch below the flask bottom,and the cork and accompanying assembly of tubes, agitator, andthermomctcr is inserted in the neck of the flask. The flask and itscontents are then heated to 100 C. with no agitation except for a slowstream of hydrogen bubbling through the oil. When 100 C. is reached theagitator is started and the hydrogen flow is increased to 0.08 cubicfoot per minute, measured at standard conditions, These hydrogenatingconditions are maintained for exactly 30 minuts, whereupon the source ofheat is removed, the agitator shut on. and the hydrogen flow stopped. Arefractive index measurement is made on a small filtered sample of thehydrogenated oil. The difference between the two refractive indexmeasurements, in butyro refractometer units, is reported as the activityvalue of the catalyst. Scrupulous cleanliness of the equipment used inthis test, and avoidance of the use of rubber in any contact with theoil, are recommended. A preliminary run under the conditions of thetest, but without refractive index measurements, is found to be a goodmeans of conditioning the equipment for use in the test in order toinsure reproducible results.

It is well known that, up to a certain point, the overall rate ofabsorption of hydrogen during the hydrogenation reaction depends on theamount of catalyst surface exposed to the liquid being hydrogenated,provided an adequate hydrogen supply is maintained (and we believe thatthis calls for maintaining an adequate supply of hydrogen dissolved inthe liquid being hydrogenated). We find that for many practical purposesan amount of catalyst equivalent to a weight of nickel amounting to from0.03 per cent to 0.10 per cent of the weight of the liquid to behydrogenated ls suiiicient when using a catalyst having an activity ofabout 4 to 6 units. Under most practical conditions there is not muchadvantage in exceeding 0.20 per cent of nickel with a. catalyst of thisactivity range because other factors, such as available dissolvedhydrogen supply, then tend to become limiting.

A very high degree of agitation is of para.- mount importance inobtaining the full benefits from the present process. We have found thatthe use of even large amounts of very active catalyst together with hightemperatures and high pressures do not enable one to obtain desirablyhigh reaction rates unless one also provides violent mechanicallyinduced agitation. We prefer direct mechanical agitation by means ofmoving agitator blades, although an equivalent result may be obtained ina reaction vessel which contains no moving mechanical parts but which isprovided with means for introducing a uid reactant, either the gas orthe liquid, or both, in one or more high velocity jets. It is our beliefthat the agitation should be so violent as to cause rapid movement ofthe liquid interface relative to the solid interface at the surface ofeach catalyst particle, as contrasted with a condition in which theliquid interface on the solid particle is relatively stationary orstagnant, and also that the agitation should be such as to break up thegas bubbles to such a great extent as to facilitate continuous renewalof the supply of hydrogen dissolved in the liquid as this supply israpidly used up in the course of the reaction. Good agitation of thissort is provided in the apparatus illustrated in the drawings when theclearance between the rotors and the stators does not exceed about threesixteenths or one fourth of an inch and when the peripheral speed of theouter edges of the rotors is of the order of six feet per second. Theuse of stators to retard the swirling action of the liquid, which wouldotherwise be induced by the rotating agitators, is importantparticularly in order to avoid a centrifugal effect which would tend tomove the suspended catalyst towards the outer walls of the vessel andwould simultaneously tend to move the gas bubbles towards the center ofthe vassel.

mamas It is appropriate at this point to consider several importantfeatures in the design of hydrogenation vessels suitable for use in ourprocess. Our requirements of a continuous and simultaneous inflow andoutflow of the oil being treated, under the conditions of extremeturbulence caused by the violent agitation, would surely result inserious contamination of the finished hydrogenated product with rawmaterial or only partially processed material if one used hydrogenationvessels resembling many of those heretofore used or proposed. It hasbeen found that this highly objectionable result may be satisfactorilyavoided by either of two alternative expedienteand preferably by acombination of both of them-each tending to retard movement ofinsuiciently hydrogenated material through and out ot the hydrogenator.

The first expedient is to employ a reaction chamber which is relativelyquite long, from entrance to exit, and which thus permits the employmentof a relatively large number of successive sets of transverse agitators,interspersed with successive sets oi stator blades, whereby the flow ofmaterial from inlet to outlet is repeatedly interrupted.

The second expedient is to subdivide the reaction zone into a series ofinterconnecting les ser zones. the interconnecting passages being sogreatly restricted in cross sectional area that the agitation occurringin one of these zones is not felt to an appreciable extent in theadjoining zone. Our circular baiiles, B0, which leave an annular passagearound the shaft just one eighth of an inch wide in a hydrogenatorhaving an internal diameter of 8 inches and a shaft diameter of 4inches, accomplish this purpose.

The horizontal circular bellies, elements B0, although preferredfeatures of the hydrogenation vessel, may ii desired be omittedentirely. In this event channeling" of insufficiently hydrogenatedmaterial to the outlet is to a large extent avoided, although not to thefull extent preferred for some purposes, when the length of the chamberfrom inlet to outlet is such as to permit the employment of at least to15 separate sets of agitators, each set separated from the next by acooperating set of stator blades.

By providing the mechanical agitation in a direction which ispredominantly transverse (preferably perpendicular or even somewhatcounter) to the main direction of ow of the liquid being hydrogenated,the agitator-impelled transfer oi' unprocessed raw material towards theoutlet of the vessel is minimized. This may be accomplished by aligningthe pressure resisting surfaces of the agitator blades and of the statorblades so that they face in a direction generally transverse to, and nottending towards, the general direction of liquid iiow. While the bladesurfaces thus define planes substantially parallel to the generaldirection of liquid iiow, slight inclination is of course permissible,and inclination tending to retard axial flow may in some cases bedesirable.

When the chief reliance for the avoidance of "channeling is placed inhorizontal bafiies such as elements 6U, with a minimum of agitatorblades-1. e. when each of the lesser zones between two horizontalbailles is provided with just one set of transverse agitators-channelingis to a large extent avoided, although perhaps not to the full extentpreferred for some purposes, by thus subdividing the hydrogenation spaceinto at least six lesser zones.

The hydrogenator used in our process is designed to provide foreflicient removal from the reactants of large quantities of heat, sincethe heat generated by the reaction amounts to about 2 B. t. u. per poundof oil hydrogenated per unit oi' iodine value drop. Thus the rate ofheat development in Example 5, wherein 1015 pounds of oil arehydrogenated per hour to a 42.5 I. V. drop, amounts to about 86,000 B.t. u. per hour. In the hydrogenatqr illustrated in the drawings, theheat transfer surface is large in relation to the cubical contents ofthe vessel, and the heat transfer coefficient is high because of theviolent agitation.

A single minimum limit for the reaction rate to be expected from ourprocess cannot be established, because of the wide ranges o1' operableconditions as set forth above, particularly in temperature and pressure.Nevertheless it is distinctly desirable to provide some guide toindicate the minimum rate of hydrogenation that should be attained forpreferred results when operating our process with different materialsand at different temperature levels.

In general, the amount and activity of the catalyst, the purity of theolly liquid and the gas. the hydrogen pressure, and the effectiveness ofthe agitation should be such as to produce at least as high a reactionrate as that indicated by line D of Figure '7 for the particulartemperature employed, an exception being those cases wherein pressuresbut slightly above atmospheric are employed in the interest of securingmaximum selectivity, in which event the rate should still exceed 67 percent of the values of line D.

Curve C oi' Figure 7 represents the attainable hydrogenation rate withpurified triglyceride oils in the iodine value range from to 70. at ahydrogen gauge pressure of pounds per square inch, using 0.1 per cent ofnickel in promoted catalyst having an activity value of 5.

Having thus described our invention, what we claim and desire to secureby Letters Patent is:

l. The continuous process of partially hydrogenating unsaturatedglycerine oils containing polyolenic double bonds and having initialiodine values above 90 to produce fats having iodine values betweenabout 60 and about 90, suitable for use in the manufacture ofshortening, which comprises: (l) flowing said oil at a temperaturebetween about 60 C.and about 180 C. into, through, and (at a pointremote from the inlet) out of confined hydrogenation zone, andcontinuously introducing hydrogen gas into said zone under a controlledand substantially uniform superatmospheric pressure not exceeding about500 pounds per square inch; (2) maintaining mechanically induced violentagitation of a turbulent character in each of at least four separatedadjoining localities along the path of said oil within said zone,thereby promoting highly effective contacting of all reactants whilesimultaneously restricting movement of the oil intermediate saidlocalities and thus retarding movement of insufliciently hydrogenatedoil through and out of said zone; (3) establishing, with the aid of acontinuously introduced supply of highly active finely dividednickel-containingcatalyst, a hydrogenation rate averaging at least asgreat as that represented by the point on line D of Figure 7 whichcorresponds to the hydrogenation temperature employed; (4) continuouslyremoving from the reaction mixture substantially all of the heatliberated by the hydrogenation reaction. thereby facilitating effectiveand constant control of the desired end point of the reaction; andcontinuously removing the hydrogenated oil from the hydrogenation zoneat an iodine value between 90 and about 80.

2. 'I'he process of claim 1. in which the unsaturated oil is vegetableoil having an iodine value between about 90 and about 140, and theactivity oi the catalyst as herein defined is at least about 4 units.

3. The process of claim 2, in which the hydrogenation temperature isbetween about 150 C. and about 180 C.. the hydrogen pressure is betweenabout pounds and about 60 pounds per square inch, and the hvdrogenationrate corresponds to an average iodine value drop oi' at least 8 unitsper minute: thereby producing base stock for plastic shortening havingsuperior keeping qualities and desirable consistencies.

4. The process oi.' claim 2. in which the hydrogenation temperature isbetween about C. and about 110 C.. the hydrogen pressure is above aboutpounds per square inch. and hydrogenation rate corresponds to an averageiodine value drop of at least 9 units per minute; thereby producing basestock for plastic shortening having superior plastic 4properties anddesirable keeping qualities.

5. The process of claim 2, in which the hydrogenation temperature isbetween about C. and 150 C.. the hydrogen pressure is atleast aboutpounds per snuare inch. and the hydrogenation rate corresponds to anaverage iodine value drop oi' not less than 5 units per minute at 110 C.hydrogenation temperature. not less than 14 units at 130" C., not lessthan 35 units at C.. the minimum rate for intermediete temperatureslving on a smooth curve connecting the said 110 C., 130 C.. and 150 C.minimum values: thereby producing base stock for plastic shorteninghaving a superior combination of keeping qualities and plasticproperties.

8. The process of claim 2, in which the hydrogenation temperature isbetween about 150 C. and about C., the hydrogen pressure does not exceedabout 20 pounds per square inch, and the hydrogenation rate correspondsto an average iodine value drop of at least 5 units per minute, and thepartially hydrogenated oil is retained in the hydrogenation zone untilits iodine value drops below about 70. thereby producins base stock forhydrogenated shortening having exceptionally good keeping qualities.

7. The process of claim 1, in which the average time required tohvdrogenate each portion of the oil does not exceed ten minutes.

8. The process of claim 2. in which the oil is cottonseed oil.

9. The process oi' claim 2. in which the oil is soybean oil.

10. The process ot claim 2. in which the oil is a mixture containingbetween 10 and 50 percent oi' cottonseed oil and between 50 and 90percent of soybean oil.

VICTOR MILLS. JUDSON H. SANDERS. HAROLD K. HAWLEY.

REFERENCES CITED The following references are ci' record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,856,120 valentine May 3, 19322,163,602 Jenness June 27, 1939 2,183,603 Jenness June 27, 19392.164.291 Jenness June 27, 1939 2,389,284 'IurckV Nov. 20, 1945

1. THE CONTINUOUS PROCESS OF PARTIALLY HYDROGENATING UNSATURATEDGLYCERINE OILS CONTAINING POLYOLEFINIC DOUBLE BONDS AND HAVING INITIALIODINE VALUES ABOVE 90 TO PRODUCE FATS HAVING IODINE VALUES BETWEENABOUT 60 AND ABOUT 90, SUITABLE FOR USE IN THE MANUFACTURE OFSHORTENING, WHICH COMPRISES: (1) FLOWING SAID OIL AT A TEMPERATUREBETWEEN ABOUT 60*C. AND ABOUT 180*C. INTO, THROUGH, AND (AT A POINTREMOTE FROM THE INLET) OUT OF CONFINED HYDROGENATION ZONE, ANDCONTINUOUSLY ININTRODUCING HYDROGEN GAS INTO SAID ZONE UNDER ACONTROLLED AND SUBSTANTIALLY UNIFORM SUPERATMOSPHERIC PRESSURE NOTEXCEEDING ABOUT 500 POUNDS PER SQUARE INCH; (2) MAINTAINING MECHANICALLYINDUCED VIOLENT AGITATION OF A TURBULENT CHARACTER IN EACH OF AT LEASTFOUR SEPARATED ADJOINING LOCALITIES ALONG THE PATH OF SAID OIL WITHINSAID ZONE, THEREBY PROMOTING HIGHLY EFFECTIVE CONTACTING OF ALLREACTANTS WHILE SIMULTANEOUSLY RESTRICTING MOVEMENT OF THE OILINTERMEDIATE SAID LOCALITIES AND THUS RETARDING MOVEMENT OFINSUFFICIENTLY HYDROGENATED OIL THROUGH AND OUT OF SAID ZONE; (3)ESTABLISHING, WITH THE AID OF A CONTINUOUSLY INTRODUCED SUPPLY OF HIGHLYACTIVE FINELY DIVIDED NICKEL-CONTAINING CATALYST, A HYDROGENATION RATEAVERAGING AT LEAST AS GREAT